JPS6317023B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing an oil hole in a hollow crankshaft by casting.

Crankshafts in which a pipe is cast into the oil hole have been known for a long time, but in conventional crankshafts, the end surface of the pipe protrudes from the machined surface of the crankshaft, such as the pin or journal part. is now the oil hole opening. Therefore, there is a drawback that the position of the oil hole opening is not constant due to variations during mold making and pipe installation.
In addition, since the pipe is protruding from the machined surface, the casting material (FCD70) and the pipe material (S material), which are made of different materials, must be turned or ground at the same time, which poses problems with surface accuracy and problems with the tools. There were also problems with longevity.

In order to solve the above-mentioned problems of the prior art, the present invention blinds both ends of the pipe by welding or a similar method, and uses a core to prevent the end surface of the pipe from protruding into the machined surface. The crankshaft is fixed and cast, and then cross holes are bored in the pipe using a drill or the like.An embodiment thereof will be described with reference to the drawings.

FIG. 1 is a sectional view showing a part of a hollow crankshaft obtained by a first embodiment of the method of the present invention. In FIG. 1, 1 is a hollow crankshaft, 2 is a cross hole, 3 is a pipe, 4 is a pin portion of the shaft 1, 5 is a journal portion of the shaft 1,
6 and 7 are the ends of the pipe 3. That is, when casting the hollow crankshaft 1, first, the ends 6 and 7 of the pipe 3 are crimped to make them blind, and one end 6 of the pipe 3 is fixed to a core (not shown) for forming the hollow part of the pin part 4. , the other end portion 7 is fixed to a hollow portion forming core (not shown) of the journal portion 5. Here, it is necessary to select the length of the pipe 3 in advance so that the ends 6 and 7 of the pipe 3 do not protrude into the machined surfaces of the pin part 4 and journal part 5. next,
The hollow crankshaft 1 is cast by pouring the metal in a conventional manner. That is, the hollow crankshaft 1 is manufactured by discharging the core sand after solidifying the molten metal. After that, cross holes 2 are drilled into the pipe 3.
to be drilled. Then, the hole 2 becomes an oil hole and the hollow crankshaft 1 shown in FIG. 1 is obtained.

In FIG. 2, one pipe 3 is fixed using two pin parts 4 and one hollow part forming core (not shown) in one journal part 5, and as in the case of FIG. After casting the hollow crankshaft 1,
A cross hole 2 is bored in the pipe 3. Of course, in the case of Figure 2, as in the case of Figure 1,
It is necessary to select the length of the pipe 3 in advance so that the pipe 3 does not protrude into the machined surfaces of the pin part 4 and journal part 5.

FIG. 3 shows that one bent pipe 3 is fixed using all the pin parts 4 and the hollow part forming cores (not shown) of the three journal parts 5, and the first
As in the case shown in the figure, the cross holes 2 are drilled after the crankshaft 1 is cast. In the case of Fig. 3, the pipe 3 is cut in advance so that the pipe 3 does not come out on the machined surface of the pin part 4 and journal part 5.
In addition to selecting the length of the pipe 3, it is also necessary to consider the shape of the pipe 3.

As described above, the present invention seals both ends of the pipe to prevent the pipe from protruding into the machined surfaces of the pin and journal parts of the crankshaft, thereby forming the hollow parts of the pin part and journal part. This method involves drilling cross holes in the pipe after fixing it to the core and casting the crankshaft, so it is difficult to drill the cross holes, that is, to accurately drill the oil hole in the predetermined position. Therefore, not only can it be easily carried out even on crankshafts with complicated oil hole shapes, but since the pipe does not protrude from the machining surfaces of the pin and journal parts, the machining can be carried out in general. This can be done under the same processing conditions as for a cast crankshaft.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention.
The figure is a sectional view showing a part of the hollow crankshaft obtained in the first embodiment, FIG. 2 is a similar sectional view in the second embodiment, and FIG. 3 is a similar sectional view in the third embodiment. It is a diagram. DESCRIPTION OF SYMBOLS 1... Hollow crankshaft, 2... Cross hole (oil hole), 3... Pipe, 4... Pin part, 5... Journal part, 6, 7... End part of pipe.

Claims (1)

[Claims] 1. A pipe with both ends sealed is fixed to the core forming the hollow part of the pin part and journal part of the crankshaft so that it does not come out onto the machined surfaces of the pin part and journal part, and then pouring molten metal, 1. A method for manufacturing an oil hole for a hollow crankshaft, comprising: manufacturing a hollow crankshaft by discharging core sand after solidification, and then drilling cross holes in the pipe.